If you get a new coupler, do you have to get it faced off? They local guy says $45 to do that.
I dont understand how a new coupler is not already machined true.[/QUOTE]

Coupler flanges do need to be machined. New or not they can be off. It is a lot cheaper, and convenient, to just get it done than have a problem and get it done later.

Keep in mind also that the shaft has tolerances as does the coupler bore and the coupler face. Once in a while even though each face, bore, shaft, are within specs. those tolerances can be additive the wrong way enough to be a problem.

Yep. get the coupling flange face skim cut while on the shaft on the lathe. Should not be necessary, but well worth it. A couple thou runout makes for an annoying wiggle. Skim cut will make it silky smoooooooth.